U.S. patent number 10,302,164 [Application Number 14/359,323] was granted by the patent office on 2019-05-28 for material for friction components of disc brakes.
This patent grant is currently assigned to FRENI BREMBO S.p.A.. The grantee listed for this patent is Lorenzo Cavalli, Andrea Gavazzi, Massimiliano Valle. Invention is credited to Lorenzo Cavalli, Andrea Gavazzi, Massimiliano Valle.
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United States Patent |
10,302,164 |
Gavazzi , et al. |
May 28, 2019 |
Material for friction components of disc brakes
Abstract
The invention illustrates a material for friction components of
disc brakes comprising between 1% and 8% by weight of at least one
preceramic resin and between 2% and 10% by weight of at least one
organic resin. It also illustrates a friction component for a disc
brake, a disc brake, and a process for producing such a
material.
Inventors: |
Gavazzi; Andrea (Bergamo,
IT), Cavalli; Lorenzo (Bergamo, IT), Valle;
Massimiliano (Bergamo, IT) |
Applicant: |
Name |
City |
State |
Country |
Type |
Gavazzi; Andrea
Cavalli; Lorenzo
Valle; Massimiliano |
Bergamo
Bergamo
Bergamo |
N/A
N/A
N/A |
IT
IT
IT |
|
|
Assignee: |
FRENI BREMBO S.p.A. (Bergamo,
IT)
|
Family
ID: |
45507818 |
Appl.
No.: |
14/359,323 |
Filed: |
November 21, 2011 |
PCT
Filed: |
November 21, 2011 |
PCT No.: |
PCT/IT2011/000381 |
371(c)(1),(2),(4) Date: |
September 25, 2014 |
PCT
Pub. No.: |
WO2013/076744 |
PCT
Pub. Date: |
May 30, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20150047930 A1 |
Feb 19, 2015 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L
83/04 (20130101); C08L 61/00 (20130101); C08L
61/06 (20130101); C08K 3/08 (20130101); F16D
69/025 (20130101); F16D 69/023 (20130101); C08L
83/04 (20130101); C08L 61/00 (20130101); C08K
3/08 (20130101); C08L 61/06 (20130101); C08K
3/08 (20130101); C08L 83/04 (20130101); F16D
65/092 (20130101); F16D 2200/0056 (20130101); F16D
2200/0043 (20130101) |
Current International
Class: |
F16D
69/02 (20060101); C08K 3/08 (20060101); C08L
83/04 (20060101); C08L 61/06 (20060101); C08L
61/00 (20060101); F16D 65/092 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1187836 |
|
Jul 1998 |
|
CN |
|
2930254 |
|
Oct 2009 |
|
FR |
|
6028484 |
|
Nov 2016 |
|
JP |
|
WO-2010015897 |
|
Feb 2010 |
|
WO |
|
Other References
Machine translation of FR 2930254, generated Nov. 13, 2016. cited
by examiner .
International Search Report and Written Opinion dated Jul. 18,
2012. cited by applicant.
|
Primary Examiner: King; Bradley T
Attorney, Agent or Firm: Merchant & Gould P.C.
Claims
We claim:
1. A material for friction components of disc brakes consisting of:
a mixture between 1% and 8% by weight of a preceramic silicone
resin and between 2% and 10% by weight of an organic resin selected
from a phenolic resin, an acrylic resin, and an epoxy resin; and at
least one catalyst, at least one abrasive agent, at least one
lubricant, at least one metal, and at least one damping agent.
2. The material for friction components according to claim 1,
wherein a total amount of preceramic silicone resin and organic
resin is less than or equal to 12% by weight.
3. The material for friction components according to claim 1,
comprising between 2% and 6% by weight of preceramic silicone resin
and between 4% and 8% by weight of organic resin.
4. The material for friction components according to claim 1,
comprising 2% by weight of preceramic silicone resin and 7% by
weight of organic resin.
5. The material for friction components according to claim 1,
wherein said preceramic silicone resin comprises at least one
silicone resin.
6. The material for friction components according to claim 5,
wherein said silicone resin is a siloxane resin.
7. The material for friction components according to claim 6,
wherein said siloxane resin is a polysilsesquioxane resin.
8. The material for friction components according to claim 1,
wherein said organic resin is a phenolic resin.
9. A friction component for disc brakes comprising a material
consisting of: a mixture between 1% and 8% by weight of a
preceramic silicone resin and between 2% and 10% by weight of an
organic resin selected from a phenolic resin, an acrylic resin, and
an epoxy resin; and at least one catalyst, at least one abrasive
agent, at least one lubricant, at least one metal, and at least one
damping agent.
10. The friction component according to claim 9, comprising at
least one pad for a disc brakes.
11. A disc brake comprising at least two pads according to claim 10
and a caliper for a disc brake comprising thrusting means suitable
for clamping said at least two pads against a braking face of a
brake disc.
12. A process for producing a material for friction components of
disc brakes comprising the following steps: providing between 1%
and 8% by weight of a preceramic silicone resin; providing between
2% and 10% by weight of an organic resin selected from a phenolic
resin, an acrylic resin, and an epoxy resin; mixing the preceramic
silicone resin and the organic resin; forming a mixture consisting
of: the preceramic silicone resin, the organic resin, at least one
catalyst, at least one abrasive agent, at least one lubricant, at
least one metal, and at least one damping agent; moulding and
polymerising the mixture so as to obtain a semifinished product;
and firing the semifinished product.
13. The process for producing a material for friction components of
disc brakes according to claim 12, wherein a total amount of
preceramic silicone resin and organic resin is less than or equal
to 12% by weight.
14. The process for producing a material for friction components of
disc brakes according to claim 12, wherein the preceramic silicone
resin is between 2% and 6% by weight, and the organic resin is
between 4% and 8% by weight.
15. The process for producing a material for friction components of
disc brakes according to claim 12, wherein the preceramic silicone
resin is 2% by weight and the organic resin is 7% by weight.
16. The process for producing a material for friction components of
disc brakes according to claim 12, wherein the preceramic silicone
resin comprises at least one silicone resin.
17. The process for producing a material for friction components of
disc brakes according to claim 12, wherein the preceramic silicone
resin comprises a siloxane resin.
18. The process for producing a material for friction components of
disc brakes of claim 12, wherein the preceramic silicone resin
comprises a polysilsesquioxane resin.
19. The process for producing a material for friction components of
disc brakes of claim 12, wherein the organic resin is a phenolic
resin.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is the 35 U.S.C. .sctn. 371 national stage of PCT
Application No. PCT/IT2011/000381, entitled "Material for Friction
Components of Disc Brakes" and filed Nov. 21, 2011, which is herein
incorporated by reference in its entirety.
The present invention relates to a material for friction components
of disc brakes.
The present invention relates also to a process for producing a
material for friction components of disc brakes, pads for disc
brakes and disc brakes comprising such pads.
In general, in a disc brake, the braking action is produced by
braking means, like for example a piston and cylinder group, which
act through friction components on opposite surfaces of a rotating
disc.
It is known to carry out friction components for disc brakes using
conventional organic materials such as phenolic resins.
Such materials, however, have strict limitations, in terms of
resistance to temperature, which means that components of
substantial dimensions have to be made, with obvious drawbacks in
the field of reference.
Therefore, recently friction components for disc brakes have been
made using ceramic matrix materials.
Indeed, ceramic matrix materials present good performance in terms
of friction coefficient and of resistance to wear. Moreover, their
characteristics of thermal refractoriness make it possible to
reduce the transmission of heat from the disc to the hydraulic
braking system, with respect to friction material obtained, for
example, by sintering metallic or organic powders.
Such ceramic matrix materials are generally obtained through
pyrolysis of polymeric ceramic precursors (polymer pyrolysis),
normally consisting of siliconic organic polymers (containing
silicon), like for example polysilanes, polycarbosilanes,
polysilazanes and polysiloxanes.
The international patent application, in the name of the same
Applicant, published at No. WO 2010/016079, describes an example of
friction material with ceramic matrix.
It discloses a process for making a ceramic matrix material for
friction components of brakes, in particular of disc brakes,
comprising the following operational phases: preparing a mixture of
at least one silicon type ceramic precursor, with particles of hard
materials suitable as abrasives, particles of substances suitable
as lubricants and particles of metallic materials; hot-press said
mixture to obtain a green body; submitting said green body to a
pyrolysis process in order to achieve ceramization of the
preceramic binder, obtaining said ceramic matrix material; in which
said mixture comprises a catalyst suitable for favouring
reticulation of said ceramic precursor during said hot-pressing
phase and in which said pyrolysis process is carried out at
temperatures below 800.degree. C.
Known ceramic materials, although they are efficient from the point
of view of thermal resistance and therefore of braking, create
vibrations and problems of noisiness during use. This greatly
compromises its use since comfort is one of the most significant
commercial requirements in the field of reference.
Indeed, it is known that, during the braking action, a noise is
often generated, which is typically in the form of a whistle, which
reduces driving comfort.
The generation of this kind of noise is attributed to the
occurrence of vibration phenomena that involve different components
of the brake, including the pads.
A great deal of researches has been carried out in order to propose
disc brake geometries that make it possible to reduce or eliminate
the noisiness of braking.
The solutions found, however, in most cases, require a redesign of
the whole structure of the brake.
The need to so deeply modify the structure of the brake to reduce
the phenomenon of whistling represents a substantial drawback.
Indeed, given the complexity of the phenomena that occur during
braking and given their dependency on the particular application,
in other words the type of vehicle in which the disc brakes are
used, a specific solution that is optimal based on theoretical
simulations can be unsatisfactory following experimental tests or
following its use for applications which differs from those
foreseen.
The object of the present invention is therefore to provide a
material for friction components of disc brakes that is resistant
to high temperatures and that achieves effective and noiseless
braking, even in small-sized components.
A further object of the present invention is to provide a friction
component which does not involve structural modifications of the
disc brake.
These and further objects are achieved through a material for
friction components of disc brakes comprising between 1% and 8% by
weight of at least one preceramic resin and between 2% and 10% by
weight of at least one organic resin.
In the present context the term "preceramic" indicates a polymeric
precursor of a ceramic material.
Thanks to the presence of such specific percentages of preceramic
resin and organic resin in the composition of the material, it is
possible to avoid the aforementioned drawbacks.
Preferably, the total amount of preceramic resin and organic resin
is less than or equal to 12% in peso.
In this way the moulding step of the material is promoted.
In accordance with a preferred embodiment of the invention, said
material for friction components comprises between 2% and 6% by
weight of preceramic resin and between 4% and 8% by weight of
organic resin.
With such percentages it is possible, apart from overcoming the
drawbacks related to noisiness and heat resistance, also to improve
performance in the running-in step of the friction components
obtained with such materials.
In accordance with a particularly preferred embodiment of the
invention, said material comprises 2% by weight of preceramic resin
and 7% by weight of organic resin.
With such percentages, a material is obtained which presents a
better compromise in terms of heat resistance and quietness of
braking.
Advantageously, said preceramic resin comprises at least one
silicone resin.
Preferably, the silicone resin is a siloxane resin. It is
particularly cost-effective.
Even more preferably, said siloxane resin is a polysilsesquioxane
resin. It is optimal for performance and wearing of the friction
material obtained therewith.
Advantageously, the organic resin is a phenolic resin.
Preferably, the material for friction components also comprises at
least one from: catalyst, abrasive agent, lubricant, metal and
damping agent. They help the tribological functions.
In accordance with a further aspect, the invention concerns a
friction component for disc brakes comprising a material as
described before and as described better hereafter.
A friction component made from such a material achieves the same
advantages of efficiency and quietness mentioned before.
It also has the advantage of having a conventional structure, i.e.
of not requiring structural modifications of the disc brake.
In accordance with a further aspect, the invention concerns a disc
brake comprising at least two pads, as described before and as
better described hereafter, and a caliper for a disc brake
comprising thrusting means suitable for clamping said at least two
pads against a brake band of a brake disc.
Such a disc brake is simple and cost-effective to produce, as well
as having all of the aforementioned advantages of efficiency and
quietness.
In accordance with a further aspect, the invention relates to a
process for producing a material for friction components of disc
brakes comprising the following steps: providing between 1% and 8%
by weight of at least one preceramic resin; providing between 2%
and 10% by weight of at least one organic resin; mixing the
preceramic resin and the organic resin; moulding and polymerising
the mixture so as to obtain a semifinished product; firing the
semifinished product.
Such a process makes it possible to produce a material with good
heat resistance and therefore a friction component that is
efficient, noiseless and small in size.
Such a method is also simple and cost-effective.
Baking is a known heat treatment that will not be detailed any
further.
In order to better understand the invention and appreciate the
advantages thereof, it will be hereafter provided a description of
some non-limiting example embodiments of the material for friction
components of disc brakes, of friction components for disc brakes,
of disc brakes and of processes for producing the material for
friction components for disc brakes, with reference to the attached
figures, in which:
FIG. 1 represents a diagram showing two functions: the top part
shows the progression of the average friction coefficient of a
friction component in a material according to a first embodiment of
the present invention, in a known organic material and in a known
ceramic material, as far as the number of braking episodes
increases, in normal operation; the bottom part shows the
progression of the temperature of the disc, associated with the
friction component during braking, as far as the number of braking
episodes increases for the same three materials;
FIG. 2 is a diagram showing the progression of the average friction
coefficient of a friction component made from a material according
to a second embodiment of the present invention, a known organic
material and a known ceramic material, as the number of braking
episodes increases, in the running in step;
FIG. 3 is a diagram showing the progression of the instantaneous
friction coefficient of a friction component of a material
according to a third embodiment of the present invention, of a
known ceramic material and of a known organic material, during
braking.
The material for friction components of disc brakes, according to
the present invention, comprises between 1% and 8% by weight (wt %)
of at least one preceramic resin.
Such a percentage is preferably between 2% and 6%. Optimal results,
with the materials given as examples, are obtained with an amount
of preceramic resin of about 2% by weight.
Some example of preceramic resins able to be used in the present
invention are: polysilanes, polycarbosilanes, polysilazanes and
polysiloxanes.
Such a preceramic resin is preferably a silicone resin, even more
preferably a siloxane resin. In the preferred embodiment it is a
polysilsesquioxane resin.
The material for friction components according to the present
invention also comprises between 2% and 10% by weight of at least
one organic resin.
Such a percentage is preferably between 4% and 8%. Optimal results
are obtained with 7% by weight of organic resin.
As will be seen from the examples, the total amount of preceramic
resin and organic resin is preferably less than or equal to 12% by
weight.
The organic resin may be selected from: phenolic resins, acrylic
resins, epoxy resins.
In accordance with the preferred embodiment of the invention, it is
preferably a phenolic resin.
The material for friction components also comprises, in a known
way, catalysts, abrasives, metals, damping agents and/or
lubricants.
In particular, the catalyst is comprised in the mixture in an
amount less than or equal to 2% by weight; the abrasive is between
10% and 30% by weight; the metals are in an amount less than or
equal to 60%; the damping agents are in an amount less than or
equal to 10%; and the lubricants are in an amount less than or
equal to 50%.
The damping agent is used to improve comfort and it preferably
comprises planar silicates.
The friction material according to the present invention may be
used to produce friction components intended to cooperate
tribologically both with brake discs made from composite ceramic
material (CCM), and with brake discs made from grey cast iron.
A friction component according to the present invention is
preferably a pad.
It has a known geometry, i.e. it is not necessary to make
particular structural modifications to the geometry of the pad
according to the invention.
A disc brake according to the present invention comprises at least
two pads and a caliper for a disc brake of the known type. Such a
caliper comprises thrusting means to clamp the pads against a brake
band of a brake disc.
The geometries of the pads and of the caliper, being of the known
type, will not be described any further.
Preferred examples of processes for producing a material of
components of disc brakes, according to the present invention, will
now be described.
A preferred process of the invention comprises to provide between
1% and 8% by weight of at least one preceramic resin and between 2%
and 10% by weight of at least one organic resin.
They are preferably in powder form.
In a subsequent step, it is provided to mix at least one of the two
resins, preferably the preceramic one, with a catalyst. Such a
catalyst comprises Zincacetylacetonatehydrate Zn(C5H7O2)2 xH2O.
Thereafter the preceramic resin and the organic resin are mixed
together.
The mixture thus obtained is added with the abrasive agent, the
lubricant, the metal and/or the damping agent.
The latter has a damping function, is used to improve comfort, and
preferably comprises planar silicates.
Then follows a step of moulding and polymerising the mixture so as
to obtain a semifinished product.
The moulding takes place through pressure moulding with a pressure
of about 150-600 kg/cm.sup.2.
Thereafter it is possible to carry out a firing step at
temperatures that are not high, for example at about 300.degree.
C.
In accordance with a first variant of the process of the invention,
the preceramic resin, in powder form, is granulated, preferably
together with abrasives, lubricants, metals, dampers and a liquid
adjuvant, preferably water. The particles that form following such
a step are left to dry, preferably at room temperature, and then
pyrolysed.
The pyrolysis preferably takes place in an inert atmosphere, for
example in nitrogen, at about 500.degree. C. in a pyrolysis
furnace.
The product thus obtained is mixed with the organic resin:
Preferably, thereafter it is added to again with one or more from:
abrasives, lubricants, metals, dampers.
The mixture is then hot moulded and polymerised. Thereafter it is
possible to carry out a firing step at a relatively low
temperature, for example about 300.degree. C.
In this way, a structure is obtained made up of an organic matrix
in which particles of ceramic material are incorporated.
In accordance with a second variant, the process of the invention
comprises providing the preceramic resin in liquid form and the
organic resin in powder. Such a variant provides moulding and
polymerising the organic resin so as to obtain an organic
semifinished product.
Thereafter, the organic semifinished product is heat treated at
about 300.degree. C. Such heat treatment preferably comprises a
firing step in ambient atmosphere.
Alternatively, the treatment takes place in modified atmosphere, in
particular in nitrogen at about 500.degree. C.
Thereafter, the preceramic resin in liquid form, combined with
optional additives, is allowed to penetrate in the organic
semifinished product so as to obtain a hybrid semifinished product
that is then pyrolysed.
Said step is preferably carried out in a vacuum to promote the
penetration of the preceramic resin in the porosities of the
semifinished product.
EXAMPLES
Example 1
6% by weight of polysilsesquioxane resin, added with catalyst, is
mixed with 4% by weight of phenolic resin.
Such a mixture is added to with 24% by weight of abrasive agent,
40% by weight of metal, 21% by weight of lubricant and 5% by weight
of damping agent.
Example 2
2% by weight of polysilsesquioxane resin, added with catalyst, is
mixed with 7% by weight of phenolic resin.
Such a mixture is added to with 24% by weight of abrasive agent,
41% by weight of metal, 21% by weight of lubricant and 5% by weight
of damping agent.
Example 3
4% by weight of polysilsesquioxane resin, added with catalyst; is
mixed with 6% by weight of phenolic resin.
Such a mixture is added to with 24% by weight of abrasive agent,
40% by weight of metal, 21% by weight of lubricant and 5% by weight
of damping agent.
Example 4 (Comparative)
9% by weight of phenolic resin was added to with 24% by weight of
abrasive agent, 41% by weight of metal, 21% by weight of lubricant
and 5% by weight of damping agent.
Example 5 (Comparative)
9% by weight of polysilsesquioxane resin, added with catalyst, is
mixed with 35% by weight of abrasive agent, 34% by weight of metal
and 22% by weight of lubricant.
With each of the five materials obtained, pads of known geometry
were made.
The pads obtained in the aforementioned examples 2u were tested
through simulation of real braking on a chassis dynamometer
reproducing the same inertia of a road vehicle.
The top part of the graph of FIG. 1 shows the progression of the
average friction coefficients of the pads according to the first
embodiment of the invention (example 1) and according to the two
materials of the prior art given, respectively, in example 4 and in
example 5, as the number of braking episodes increases, in normal
operation.
As it can be seen from such a graph, the material according to the
invention maintains a substantially constant average friction
coefficient as the number of braking episodes increases. This
demonstrates that is maintains good mechanical characteristics.
Moreover, the material of the invention does not have the negative
peaks of the organic material and therefore there are no sudden
decreases in braking efficiency.
In the bottom part of the graph of FIG. 1, it can be seen how the
temperature of the disc associated with the pads themselves varies,
as the number of braking episodes increases. The temperature of the
disc with pads made from material of the invention is lower than
the temperature of the disc with pads of organic material (example
4), with obvious mechanical advantages.
From such a FIG. 1 it can thus be seen how the friction coefficient
of the pads made with the material according to the invention
remains high even at high temperatures.
The graph of FIG. 2 shows the progressions of the average friction
coefficients of the pads according to the second embodiment of the
invention (example 2), i.e. the particularly preferred embodiment,
and according to the two materials of the prior art given,
respectively, in example 4 and in example 5, as the number of
braking episodes increases, during a running in step. As it is well
known, the running in step is a delicate step in which it is more
difficult to ensure a constantly high friction coefficient.
As it can be seen from such a graph, the material according to the
invention maintains a substantially constant and high average
friction coefficient as the number of braking episodes increases,
even during running in. Such an average friction coefficient is
also on average greater than the friction coefficient of organic
material. Therefore, the braking efficiency of pads made with the
material of the invention is greater than the braking efficiency of
pads made from known organic material (example 4).
The graph of FIG. 3 gives the progression of the instantaneous
friction coefficients of the pads according to the third embodiment
of the invention (example 3) and according to the two materials of
the prior art given, respectively, in example 4 and in example 5,
during braking.
As it can be seen from such a graph, the material according to the
invention maintains a substantially constant instantaneous friction
coefficient during braking, and in any case greater than known
organic material (example 4).
The pads obtained with the aforementioned five materials were also
subjected to comfort tests, i.e. noisiness tests.
Whereas the pads of example 5, i.e. the ceramic ones, proved to be
noisy, the remaining four pads gave good results, i.e. they proved
to be sufficiently noiseless and comfortable.
From the results of the tests it can be seen that the material of
friction components for disc brakes according to the present
invention has a substantially constant average friction
coefficient, similarly to the case of ceramic material.
In other words, the performance of the material of the invention,
in terms of braking efficiency, is as good as the performance of
ceramic materials.
On the other hand, organic material is subject to rapid degradation
of the friction coefficient, i.e. it does not withstand high
temperatures, quickly losing braking efficiency.
Comfort tests have shown that the performance of the materials
according to the invention is as good as that of organic materials,
i.e. better than ceramic materials.
In conclusion, the materials for friction components according to
the invention, and therefore the friction components obtained
therewith, have good mechanical characteristics and excellent
comfort.
Of course, it is possible to vary the composition of the material
of the invention, within the indicated ranges, according to the
specific requirements. In other words, if particularly high
mechanical characteristics were required, a percentage of
preceramic resin close to 8% could be used. Similarly, if the
particular application were to require good characteristics in
terms of comfort, a percentage of organic resin close to 10% could
be used.
In the above description and in the following claims, all of the
numerical magnitudes indicating amounts, parameters, percentages,
and so on should be taken to be preceded in all circumstances by
the term "about" unless indicated otherwise. Moreover, all of the
ranges of numerical magnitudes include all of the possible
combinations of maximum and minimum numerical values and all of the
possible intermediate ranges, as well as those specifically
indicated in the text.
Of course, the man skilled in the art, in order to satisfy
contingent and specific requirements, can bring further
modifications and variants, all of which are in any case covered by
the scope of protection of the present invention, to the material
for friction components, to the friction components, to the disc
brakes and to the process for producing the material for friction
components according to the present invention.
* * * * *